1. Field of the Invention
The present invention relates to encapsulated heating element fluid heaters for heating a fluid such as water and more particularly pertains to a new encapsulated heating element fluid heater for heating a fluid such as water.
2. Description of the Prior Art
The use of encapsulated heating element fluid heaters for heating a fluid such as water is known in the prior art. More specifically, encapsulated heating element fluid heaters for heating a fluid such as water heretofore devised and utilized are known to consist basically of familiar, expected and obvious structural configurations, notwithstanding the myriad of designs encompassed by the crowded prior art which have been developed for the fulfillment of countless objectives and requirements.
Known prior art encapsulated heating element fluid heaters for heating a fluid such as water include U.S. Pat. No. 4,687,138; U.S. Pat. No. 3,997,114; U.S. Pat. No. 5,662,269; U.S. Pat. No. 3,760,982; U.S. Pat. No. 3,645,420; U.S. Pat. No. 5,529,460; U.S. Pat. No. 3,134,889; EPO Patent No. EP 0 515 0173 A1 (Inventor: Pirl); PCT Patent No. WO 86/07628 (Inventor: Sten); U.S. Pat. No. 5,292,056; U.S. Pat. No. 4,345,549; U.S. Pat. No. 4,364,161; and PCT Pat. No. WO 97/31748 (Inventor: Swidwa).
Encapsulated heating element fluid heaters typically comprise a vessel with an open end and an end cap having a plurality of heating element rods extending through bores in the end cap. A sealing material such as an electrically insulating epoxy is used to seal the space around each of the heating element rods in the bores of the end cap. The heating element rods are inserted into the vessel through the open end of the vessel until the end cap covers the opening of the vessel. The end cap is then coupled to the vessel to form a water-tight closure of the opening of the vessel. Fluid, such as water, is then passed through the interior of the encapsulated heating element fluid heater to be heated by the heating element rods. Encapsulated heating element fluid heaters are generally quite large in size and are required to withstand large amounts of pressure from the fluid passing through them. Because of this pressure, the seal between the open end of the vessel and the end cap must be quite strong.
In prior art encapsulated heating element fluid heaters, the vessel is usually constructed with an outwardly radiating flange around the open end of the vessel while the end cap is also constructed with a corresponding outwardly radiating flange around the end of the end cap being inserted into the open end of the vessel. These flanges are then bolted together to form a water tight coupling between the vessel and the end cap. A gasket may also be provided between the flanges to help ensure a water tight seal between the vessel and end cap. Because this coupling must be strong enough to withstand the high fluid pressures exerted from fluid in the interior of the encapsulated heating element fluid heater, these flanges on the vessel and the end cap tend to be rather large and extremely heavy.
This large size and weight makes can lead to problems in the use in typical applications of the prior art encapsulated heating element fluid heaters. For example, in portable applications, such as steam and fluid cleaners, which must be able to be easily moved about a work site by a user, the large size and weight of these types of prior art encapsulated heating element fluid heater cause problems with uneven distribution of weight of the application which makes the application unevenly balanced and easy to tip over. The large size and weight of the prior art encapsulated heating element fluid heater also makes it more difficult to lift applications using prior art encapsulated heating element fluid heaters.
One solution to reducing the weight of encapsulated heating element fluid heater is to remove the flanges from the vessel and the end cap and weld the vessel and end cap together. Removal of the flanges can reduce the weight of an encapsulated heating element fluid heater by more than 60 percent thereby making portable applications of the encapsulated heating element fluid heater more practical. However, there are several problems with this solution. One major problem with this welding solution is than the weld between the vessel and the end cap must be very strong to withstand the interior fluid pressures during use. To form a weld that is strong enough to achieve this, the area of the weld between the vessel and the end cap must be heated to a hot temperature. This heating causes the temperature of the entire end cap to heat up which leads melting the epoxy seals around each of the heating element rods in the end cap. Melting of the seals causes leaks in the encapsulated heating element fluid heater and also increases problems with the heating element rods shorting out when energized. Because of the risk of melting these seals, manufacturers of encapsulated heating element fluid heaters strongly warn against welding the end cap to the vessel, especially without use of any flanges on the vessel and end cap.
While these devices fulfill their respective, particular objectives and requirements, the aforementioned patents do not disclose a new encapsulated heating element fluid heater. The inventive device includes a vessel and an end cap. The end cap has a plurality of bores therethrough extending between the first and second ends of the end cap. A plurality of elongate heating element rods extend through the bores of the end cap and each heating element rod has a heating portion outwardly extending from the first end of the end cap and an electric coupling portion outwardly extending from the second end of the end cap. The first end of the end cap is inserted into an open end of the vessel such that the heating portions of the heating elements extend into the vessel. The end cap is then welded to the end of the vessel.
In these respects, the encapsulated heating element fluid heater according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in so doing provides an apparatus primarily developed for the purpose of heating a fluid such as water.